Dead reeds on Chromonica 270

Hello Remf3
Without the benefit of actually hearing what you are hearing, my initial suspicion point towards sticking and/or missing wind savers--not a faulty reed.

Unlike our diatonic harmonicas, where the blow reeds are secured above the draw reed, the Hohner 270 Chromatic rivets the blow and draw reeds next to each other. In order to restrict air direction to the intended reed, a one way valve--called the wind saver was adhered onto the backside of all the reed plate slots.

A fairly common mantra can be heard among chromatic harmonica players, "wind savers can be the chromatic harmonica's best friend or worst enemy! When wind savers become distorted and/or caked with Harmonicoccus, they render the instrument unplayable.

TRY THIS:
1.Remove the cover plates
2.While you are under the hood, examine all four reeds (with hardly any effort, can you push the reed in/out of the slot?).
3.Next, you will examine the four wind savers in chamber #2 for flatness (two inside the chambers and two outside the chambers).
4.With the slider OUT, examine the top #2 blow windsaver (pointing away from the mouthpiece) and make certain it is flat over reed plate slot #3 (E)
4.Direct a flashlight into the top #2 hole, peer inside the chamber and make certain the wind saver is flat and covering reed slot #4 (F) If the inside wind saver has simply curled out of position, with a straightened paper clip attempt to lift and shift the wind saver back over the slot
5.With the slider IN, repeat above steps for the bottom #2 pair of wind savers (F and Gb/F#)

Please check in with me after you have performed the recommended steps. If you are still having problems, we will move on to more trouble shooting tips.

Your Harpsmith,
Kinya

It could also be that you're experiencing the common 2-draw problem of pre-bending. This phenomenon is well known on the diatonic harmonica but occurs just as frequently on the chromatic.

Pre-bending is the phenomenon in which a player unintentionally depresses the pitch of a note by tuning his/her mouth to a lower pitch. For some unknown reason, this most often shows up on Draw 2. If the same thing is happening with the slide in, and the reeds vibrate freely at correct pitch when plucked and the valves function normally, then I'd say you might look at what you're doing with your tongue (and maybe throat) when you play these notes. Aim for an open, unimpeded air flow, with no suction or drag (think big yawn).

You may say, "But I don't have this problem when I play diatonic!" Maybe not, but the reeds in a chromatic are much more sensitive to bending, contrary to popular belief. Consequently, things that you're doing that might depress pitch may show up unannounced on chromatic. Eliminating those things will improve you sound on both instruments.